In the past, a number of zoom lens systems having a high zoom ratio comprising positive-negative-positive-negative-positive lens groups have been proposed. Also, this idea was disclosed in Japanese Patent Kokai (laid-open patent application) No. S57-164709 (1982). This lens proposed to cover a field angle of 2.omega.=64.degree. and a zoom ratio on the order of approximately 3.7.times.. Later, Kokai No. S63-266415 (1988) proposed a zoom lens with a field angle of 2.omega.=62.degree. and a zoom ratio of approximately 9.times.. More recently, Kokai No. H4-186212 (1992) disclosed a zoom lens made up of six lens groups (positive-negative-positive-negative-positive-negative), with a field angle of 26.omega.=62.degree. and a zoom ratio of approximately 9.times..
The zoom lens of Kokai No. S57-164709, however, actually had a zoom ratio on the order of 3, and a field angle of only 62.degree.. With the optical system configuration/refractive power placement (the placement/distribution of refractive power along the optical axis) as disclosed in this Kokai, or that along an extension thereof, it would be extremely difficult to obtain a zoom lens covering a field angle in excess of 2.omega.=75.degree. with magnification ratio of around 10.times.. Also, although Kokai No. S63-266415 and Kokai No. H4-186212 provide a good level of correction for aberrations, like the lens disclosed in the above Kokai, they provide field angles on the order of only about 62.degree.. And there is a need for a zoom lens with a higher zoom ratio and larger field angle than is presently available.